Foamed-in-place metal skin covered insulating panels for walk-in refrigerators and refrigerated warehouses are known in the prior art including panels having built-in attaching or locking means to connect adjacent panels of an insulated wall. It is difficult to fabricate the panels with fastening bar assemblies in place between jig fixtures when the insulating foam, such as polyurethane foam, is introduced into the cavity formed by the metal skins and end jig fixtures. The problem is to keep the insulating foam from entering and fouling the operation of the panel connecting or locking means. Customarily in the prior art, an enclosed or shielded rotary cam lock or hook-type fastening assembly has been employed successfully. However, the deficiencies and comparative weakness of this form of fastener are recognized, and ideally, for the sake of simplicity, economy and maximum strength and security, a screw-threaded connecting or locking means for adjacent insulating panels has been sought, but heretofore has not been available on a production basis primarily because of difficulties in installing the screw-threaded means within a foamed in-place panel. The particular problem which has been successfully solved by the invention is to protect the screw-threads of the fastener means from being fouled with the insulating foam during the fabrication of the panels.
The invention solves or overcomes this difficult problem by providing a simple and ingenious retaining and shielding means for the male lag screw at one end of the fastening bar assembly and by plugging the female threaded coupling member at the other end of the assembly during the foaming operation. The resulting panel construction, in terms of its built-in locking or fastening means, is far superior to the prior art, both in terms of strength or security and in economy of manufacture. Adjacent panel sections of an insulated wall can be drawn together and secured much more tightly and positively by the threaded means of the invention than by the prior art cam-type locking means. The essential method of forming the insulated panels is not interfered with in the slightest by the use of the invention.
Other features and advantages of the invention will be recognized by those skilled in the art during the course of the following detailed description .